1. Field of the Invention
This invention is in the field of safety locks for revolver type handguns.
2. Description of Prior Art
Numerous attempts have been made to devise practical safety locks for revolvers, but they have not met widespread acceptance, for reasons exemplified by the following prior patents. Some have protrusions at the muzzle and therefore are obvious to the observer. Some can be unlocked by anyone. Some are awkward and slow to set up. Many are complex and costly to manufacture. Some use materials or mechanisms in ways that are unreliable over time. Some require modification of the gun, and can only be provided as original equipment on new guns.
U.S. Pat. No. 4,048,741 (Chiodo) shows a Rotation-Preventing Lock Assembly for revolver type pistols. It is inserted into one of the firing chambers from the back, and fixed therein with a cam that is operated by a key inserted through the device from the back. This device is not aligned with the barrel, but blocks rotation of the cylinder by projecting from the back and/or front of the cylinder against the gun body. It is mechanically and operationally dissimilar to Applicants' device, and is more complex. It does not block the chamber aligned with the barrel, which can contain a live round that can accidentally discharge on some types of revolvers if the gun were dropped.
U.S. Pat. No. 4,023,294 (Knopp) shows a Safety Device for Firearms, comprising a rod that is pushed into the barrel from the muzzle, filling the barrel and firing chamber. Resilient longitudinal ribs on the rod press against the inner walls of the barrel to retain the rod in the barrel. A removable key is threaded onto the muzzle end of the rod for removal of the rod. Unlike the present invention, Knopp's device must be specialized for the barrel length of each gun. If Knopp's lock is used in a longer barrel than one for which it was designed, the rod can be inserted fully into the barrel without reaching the chamber. This would allow the gun to be fired with the rod in the barrel, not only failing to lock the gun, but creating a possibility of gun explosion.
U.S. Pat. No. 3,360,880 (Finnegan) shows a Safety Device Insertable in the Chamber of a Firearm, comprising a cylindrical casing with helical slots, a plunger extending from the casing with pins guided in the slots, and a spring urging the plunger to extend. The slots have locking seats to hold the plunger either fully extended or retracted. In the extended position the plunger blocks the gun barrel, and prevents rotation of the cylinder of a revolver. This device requires a spring, has more parts than the present invention, and has a more difficult method of use.
U.S. Pat. No. 3,072,674 (Mahan) shows a Safety Lock for Revolvers comprising a dummy cartridge with an extendable plunger in place of a bullet. The plunger is constantly urged to its extended position by a spring in the cartridge case. The dummy cartridge is inserted in a firing chamber of the cylinder. The plunger is depressed manually while rotating the cylinder, to align the dummy cartridge with the gun barrel. The plunger extends into the barrel, blocking rotation of the cylinder. To unlock the gun, a rod is inserted in the barrel to depress the plunger while the cylinder is opened for removal of the dummy cartridge. Unlike the present invention, the gun cannot be used without removing the dummy cartridge from the chamber, because the extended plunger blocks the cylinder rotation against the outer surface of the gun frame. This can cause an unacceptable delay when the gun is needed for self defense.
U.S. Pat. No. 3,022,598 (Wikstrom) shows a Safety Device for a Revolver, comprising a dummy cartridge with an extendable bullet that is continuously urged to retract into the cartridge by a spring. The bullet can be pulled forward partly into the barrel by a key inserted through the barrel. The key fits into a key-hole in the bullet, and is turned 90 degrees to interlock in the bullet. The key is then pulled forward, pulling the bullet partly into the barrel, and a clip is inserted through the shaft of the key at the muzzle to retain the key against the spring tension. To release the lock, the clip is removed, and the key is pushed inward and 90 degrees to slip it out of the key-hole. Unlike the present invention, this device requires the key to always be in the barrel of the locked gun, making it available for use by a burglar as well as the gun owner.
U.S. Pat. No. 2,530,560 (Young) shows a Safety Lock for Firearms comprising a dummy cartridge that is locked into the firing chamber by radial expansion. With this design, a dummy cartridge is required for each chamber of a revolver, making the gun useless for self-defense.
U.S. Pat. No. 2,943,411 (Salva) shows a Safety Lock for Revolvers comprising a bolt passing through a chamber of the cylinder beside the gun body, and fastened with a threaded knob. This blocks rotation of the cylinder, but does not block the firing chamber aligned with the barrel. Thus a live cartridge could be in the aligned chamber, and could accidentally discharge on some types of revolvers if the gun were dropped.